Method and apparatus for signal power loss reduction in RF communication systems

ABSTRACT

Multiple power amplifiers in an RF front end are coupled to multiple antennas without diversity switching between the PAs and antennas. Diversity switches direct signals to broadcast by a selected antenna to a PA coupled to the selected antenna. Multiple LNAs are similarly coupled to the diverse antennas. Having one PA and LNA set for each antenna removes the need for diversity switching between the PA/LNAs and each antenna improving signal reception. In one embodiment, a single external PA performs broadcast functions and plural on-chip LNAs are used for reception. In another embodiment, phase shifters are coupled to each PA and LNA, which provide beam forming capability for broadcasts, and in phase signal combinations for received signals.

COPYRIGHT NOTICE

[0001] A portion of the disclosure of this patent document containsmaterial which is subject to copyright protection. The copyright ownerhas no objection to the facsimile reproduction by anyone of the patentdocument or the patent disclosure, as it appears in the Patent andTrademark Office patent file or records, but otherwise reserves allcopyright rights whatsoever.

BACKGROUND OF THE INVENTION

[0002] 1. Field of Invention

[0003] The present invention relates to reduction of signal power lossin communications systems. The invention is more particularly related tothe reduction of signal power loss in wireless RF systems. In addition,the invention relates to implementing antenna diversity in wirelesssystems.

[0004] 2. Discussion of Background

[0005] The use of multiple antennas has become a popular method ofimproving performance of wireless devices. A simple technique is called“switch diversity”, where a radio can alternatively transmit and receivethrough separate antennas, using only one antenna at a time. The radiocan then decide which antenna to use based upon the success of previouscommunications. FIG. 1 is a diagram of a traditional “switch diversity”architecture. A pair of antennas, Antenna A and Antenna B (diversityantennas 100) are located at diverse physical locations and/or areantennas having diverse physical properties (gain, directivity, etc.).The diversity antennas 100 are connected to a diversity switch 110 thatconnects the antennas to a transmit receive switch 120. Whentransmitting, RF Mixers/Baseband device 140 feeds a signal to a poweramplifier 132 in RF front end 130. The transmit receive switch 120directs the amplified signal to the diversity switch 110 which directsthe amplified transmit signal to a selected one of the diversityantennas. When receiving a reverse signal flow occurs, except that thereceived signal is boosted by an LNA 134 prior to being received by theMixers/Baseband device 140.

[0006] The diversity switch 110 is controlled by software or otherelectronics that selects one of the diversity antennas forreception/transmission. Selection criteria is typically based on qualityof signal, S/N ratio, and/or other identifiers, such as packet receptionerrors, etc. For example, a typical arrangement would call for thebaseband and mixers 140 to include some processing or algorithm whichactivate a control signal to perform the switching. The processing wouldinclude receiving packets on each of the antennas for a length of time(or number of packets), and then compare the number of packet errorsreceived by each of the antennas. The antenna with the least number oferrors or the highest S/N ratio is then selected forbroadcast/reception. Once an antenna is selected, transmission/receptioncontinues on the selected antenna. Periodically, the other antenna(s)are re-tested. In the event a re-test indicates an environment change orother factor is degrading performance of the selected antenna comparedto the other antenna(s), the selected antenna is changed to the thenbest performing antenna.

SUMMARY OF THE INVENTION

[0007] The present inventors have realized various inefficiencies,particularly signal losses, that occur through standard diversity andtransmit/receive architectures. The present inventors have developedcertain improvements in wireless signal reception, particularly whenapplied to antenna diversity architectures, and transmit/receivearchitectures. One problem recognized is the loss incurred through thediversity and transmit/receive switches. The switches attenuate the RFsignal and introduce noise, which degrades the performance of the PA andLNA when measured from the antenna port.

[0008] The present invention provides an architecture, method, anddevice wherein redundancies at the front end of an RF device can reducelosses that occur at the diversity switch. In highly integrated radiosystems, silicon area is inexpensive and the cost of redundancy is low.The losses incurred by the diversity switches can be reduced byduplicating the number of PAs/LNAs as well as moving the antennadiversity switches from between the PA/LNA and antenna to after thePAs/LNAs.

[0009] In one embodiment the present invention is an RF front end,comprising, at least one power amplifier configured to transmit signalsto at least two antenna ports, and at least two LNA devices, each LNAdevice configured to receive signals from one of the antenna ports. Theinvention may also be embodied in an RF device, comprising, at least twoantenna ports, an RF front end having at least two PA amplifiers, eachPA amplifier having an output coupled to one of the antenna ports, an RFsignal generating device, and an antenna diversity switch coupled to theRF signal generating device and the RF front end, wherein said antennadiversity switch is configured to direct RF signals generated by the RFsignal generating device to one of the PA amplifiers.

[0010] The present invention may also be embodied as a method oftransmitting RF signals, comprising the steps of, preparing an RF signalfor transmission, selecting an antenna best suited for transmitting theprepared RF signals from a set of at least two antennas, and feeding theprepared RF signals to a power amplifier coupled to the selectedantenna; and/or a method of receiving RF signals, comprising the stepsof, determining at least one antenna best suited for receiving RFsignals, and switching a signal receiving line to an output of an LNAcoupled to one of the best suited antennas.

[0011] Portions of both the device and method may be convenientlyimplemented in programming, data sequences, and/or control signalsexecuted or generated on a general purpose computer. Any components ofthe present invention represented in a computer program, data sequences,and/or control signals may be embodied as an electronic signal broadcast(or transmitted) at any frequency in any medium including, but notlimited to, wireless broadcasts, and transmissions over copper wire(s),fiber optic cable(s), and co-ax cable(s), etc.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more complete appreciation of the invention and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

[0013]FIG. 1 is a block diagram of a traditional switch diversityantenna architecture;

[0014]FIG. 2 is a block diagram of a redundant front end architecture ina diversity antenna device according to an embodiment of the presentinvention;

[0015]FIG. 3 is a block diagram of a half redundant front end in adiversity antenna device according to an embodiment of the presentinvention;

[0016]FIG. 4 is a block diagram of a beam forming architecture usingmultiple integrated PA and LNA blocks according to an embodiment of thepresent invention;

[0017]FIG. 5 is a circuit diagram of a conventional implementation of anon-chip LNA;

[0018]FIG. 6 is a circuit diagram of an example implementation of anon-chip LNA having switching pairs for steering current according to anembodiment of the present invention;

[0019]FIG. 7 is a circuit diagram of an example implementation of anon-chip amplifier that enables beam-forming according to an embodimentof the present invention;

[0020]FIG. 8 is a circuit diagram of an example implementation of abeam-forming PA according to an embodiment of the present invention;

[0021]FIG. 9 is a graph of example antenna radiation patterns resultingfrom the circuit of FIG. 8;

[0022]FIG. 10 is a prior art implementation of a switchable powercombiner using parallel shunt PA devices;

[0023]FIG. 11 is a block diagram of a transmitter PA and a receiving LNAoperating with shunt switches in conjunction with a single antennaaccording to an embodiment of the present invention;

[0024]FIG. 12 is an example implementation of a PA with a built-in shuntswitch according to an embodiment of the present invention;

[0025]FIG. 13 provides an example implementation of beam forming bysignal phase shifting according to an embodiment of the presentinvention;

[0026]FIG. 14A is a radiation diagram for a pair of antennas configuredwithout the additional mixers shown in FIG. 13;

[0027]FIG. 14B is a radiation diagram illustrating the jB combinationsaccording to the example implementation of FIG. 13;

[0028]FIG. 14C is an effective radiation diagram combining A+-jbradiation patterns of FIG. 14B with the radiation patterns of FIG. 14A;

[0029]FIG. 15 is an example circuit implementation of the LNAs and 1stcombiner from FIG. 13 according to an embodiment of the presentinvention; and

[0030]FIG. 16 is a circuit diagram of an example implementation of themixers M1, M2, and adder of FIG. 13 according to an embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Referring again to the drawings, wherein like reference numeralsdesignate identical or corresponding parts, and more particularly toFIG. 2 thereof, there is illustrated a block diagram of diversityantenna according to an embodiment of the present invention. Theillustrated embodiment provides a framework from which signal lossesincurred due to a diversity switch can be reduced.

[0032] The signal affected most by inefficiencies, and thereforepresenting the greatest design challenge is the signal as it istransmitted to and received from the antenna. The signal is received,for example, at antenna A, and is then directed, by transmit/receiveswitch 205, to the LNA 220. In the previous designs, a diversity switchwas also included in the signal path from the antennas to the LNA.However, in the invention, RF front end 200 has an architecture thatuses redundant front end components that eliminates the need for adiversity switch between the front end and the antennas.

[0033] In FIG. 2, the baseband and mixers provide a signal to betransmitted. The signal to be transmitted is amplified as required tocounteract any losses that occur at a diversity switch 240. Thediversity switch 240 sends the signals to be transmitted to one of afirst PA 215 and a second PA 225. The diversity switch 240 is set tosend the signal to be transmitted to PA 215 when Antenna A is theselected antenna for transmissions. Reversing that process, whenreceiving signals, and antenna A is the selected receiving antenna,signals received at antenna A are routed through LNA 220, where they areamplified, and then sent through diversity switch 240 to the basebandand mixers 250. When the selected antenna is antenna B, similarprocesses occur except that the transmit signals are routed through PA225 and received signals are routed through LNA 230.

[0034] Therefore, redundant architecture of RF front-end 200 implementsa switch diversity scheme without the need for a diversity switchbetween the RF front-end and the antennas, improving the systemperformance. The diversity switching function is accomplished in a lessperformance critical section of the radio. Additional power usage isaverted because the unused half of the RF front-end can be powered down(i.e., when transmitting/receiving on antenna A, PA 225 and LNA 230 arepowered down).

[0035] If the PA and LNA are integrated parts of a largerradio-on-a-chip, the incremental cost of the silicon area to duplicatethe PA and LNA layouts is relatively small. The primary cost of thisapproach is the need to multiply the number of package pins required forthe PA and LNA ports by the number of diversity antennas beingimplemented. The transmit/receive switches 205 and 210 can either beintegrated or off-chip.

[0036] This architecture could also be used with discrete components forthe PAs and LNAs, but the cost of discrete components could beprohibitive because of the need to buy multiple PA and LNA components.If discrete external components are necessary due to performanceconstraints, a modified version of the redundant diversity architectureallows for the use of a single external component.

[0037]FIG. 3 is a block diagram of a half redundant front end 300 in adiversity antenna device according to an embodiment of the presentinvention. The half redundant front end 300 is attached to diversityswitches 340. The diversity switches 340 direct incoming signals fromeither LNA 305 or LNA 310, each on-chip devices, to the baseband andmixers 250. Signal to be transmitted, from the baseband and mixers 250are routed to an external Power Amplifier (PA) 315. The external PA thenpowers one of the antennas according to setting of switches 320 and 325.

[0038] The half-redundant architecture of RF front-end 300 duplicatesthe layout of the on-chip components, mainly the LNA, where theincremental cost is small, while avoiding the cost of duplicatingexternal components. In the example above, an external PA and aredundant LNA is used, but a similar architecture with a redundant PAand an external LNA could be used.

[0039] Using the half-redundant architecture, the performance of theexternal component may be compromised because of having to drive twoswitches (e.g., switches 320 and 325). The finite isolation of theswitch that is off will allow some fraction of power to be diverted fromthe intended path. However, the use of an external component may provideenough power margin to overcome this loss. In the example above, theperformance of the external PA may be compromised, but the loss from theantenna to the LNAs is still lower than a traditional architecture witha diversity switch between the RF front-end and the antennas.

[0040] In another embodiment, multiple LNA and/or PA devices areimplemented on-chip, one dedicated to each antenna. More than one ofthese devices can operate at a given time, enabling the simultaneous useof multiple antennas, or equivalently the use of one multi-elementantenna.

[0041]FIG. 4 is a block diagram of a beam forming architecture usingmultiple integrated PA and LNA blocks according to an embodiment of thepresent invention. RF front end 400 includes a power amplifier (PA)(e.g., PAs 405 and 410) and an LNA (e.g., LNAs 415 and 420) for eachantenna. Although the figures presented herein mainly show two antennas,any number of antennas may be utilized. In the beam forming embodiment,for example, three, four, or more antennas may be utilized, each antennahaving an additional set of LNA and PA that is preferably on-chip.

[0042] Each PA is shown feeding a transmit receive switch and acorresponding antenna. For example, PA 410 feeds transmit/receive switch430 and antenna A, and PA 405 feeds transmit/receive switch 435 andantenna B.

[0043] An input signal to be transmitted (from baseband and mixers 460)is split to feed each of the PAs. In a component based implementation asplitter 441 is utilized to split the signal. in an integratedimplementation a shared line may be utilized.

[0044] One of the PAs (e.g., 405/410) is operational when the device isbeing operated in the single antenna mode, and both PAs are operationalwhen transmitting in a beam forming or multiple antenna mode. Again,other PAs and corresponding antennas may be utilized and included in thebeam forming or multi antenna element modes, or any one or more of thePAs and corresponding antennas may be shut down when the correspondingantenna is either being used for receiving or not utilized. Any numberof combinations of transmitting, receiving, and/or unutilized PA andantenna combinations is possible to match any system requirements.

[0045] Each LNA is fed a received signal from one of the antennas,through a corresponding transmit/receive switch. Outputs of the LNAs arecombined (at adder 450) when the device is in a multi antenna elementconfiguration. Any one or more LNA outputs may be excluded from theadder operation if that LNA/antenna are idle, or, when that LNA/antennaare being used in a transmit capacity.

[0046] Thus, in the embodiment of FIG. 4, the on-chip diversity switchesdiscussed previously are replaced by appropriate signal combiners (e.g.,adder 450) at the outputs of the LNAs and signal splitters which providethe inputs to the PAs. The properties and advantages of multi-elementantennas are well documented in literature. By adjusting the phase withwhich the signals are combined from or split between the multipleantennas, the radiation diagram of the antennas (beam forming) can beadjusted and significantly improve the antenna gain towards the desireddirection, with respect with what is achieved with a single antenna. Theadjustment may be made by trial and error or based on an algorithm thattries different phase adjustments and extrapolates the results of thedifferent phase adjustments to a best phase from which to combine thesignals with. FIG. 4 provides a preferred configuration. Blocks A_(/1),A_(/2), A_(p1), A_(p2) (442-448) are programmable phase shifters. Usingappropriate circuit techniques, these blocks can be implemented in a waythat does not incur an appreciable cost in terms of performancedegradation, power consumption, or silicon area. The implementation isfacilitated if the phase shifters are capable to implement only a finiteset of signal phase rotation (for example, 0°, 180°, and 90°) as opposedto implementing an arbitrary signal phase rotation which is alsorealizable. The finite number of phase rotations reduces performancewith respect to an arbitrary phase rotation, but by only a small amountand reduces complexity and cost. The use of multiple LNAs and PAs doescome at the price of increased power consumption, but it is possiblethat lower performance and lower power circuit blocks can be used andstill benefit from the new architecture. Because the performanceimprovement provided by this technique might be enough to eliminate anexternal LNA or PA, this technique can be used to provide significantsystem power and form factor reduction.

[0047] To illustrate the benefit of this configuration in an integratedreceiver consider, for example, that the signal is being received withthe same power from the two antennas and its phase is adjusted in theblocks A_(/1) and A_(/2) such that the two signals add in phase. Thesignal level is then 6 dB higher than in the case that a single antennais used. The noise received by the two antennas and introduced by thetransmit/receive switches and all the circuitry in front of thecombiners is uncorrelated in the two paths and the output of thecombiner has 3 dB higher noise level than the LNA output in the singleantenna case. Therefore, the SNR improvement is 3 dB. In addition, sincethe signal level is higher at the combiner output than in the singleactive LNA case, the noise contribution of the rest of the receiverchain (mixers and baseband) is lower.

[0048] On the transmitter side, consider an example where the two PAsare fed with equal amplitude signals, shifted in phase appropriately byblocks A_(p1), and A_(p2) such that the outputs of the two antennas addconstructively in phase at the desired direction. Then the transmittedsignal is 6 dB higher than in the single antenna case assuming that theinput signal to the single PA is equal to the signal to each one of themultiple PAs. Since the amount of transmitted power at the desireddirection is usually defined by the system requirements, we can reducethe signal power fed to each PA, with a significant linearity benefitwith respect to the single PA case. Since each PA needs to transmit onlythe fourth of the power of the single PA case, the power consumption inthe two PAs can be significantly lower than twice the power consumptionin the single PA case.

[0049] As stated before, the on-chip diversity switches, as well as thesignal combiners and splitters can be implemented on-chip in variousefficient ways.

[0050]FIG. 5 is a circuit diagram of a conventional implementation of anon-chip LNA. LNA 500 includes Cascode devices (e.g., 506/508) providefor reverse isolation and stability. The dual outputs 510A/510B, anddual inputs 505A and 505B indicate a differential design. Bias and otherdetails are omitted to enhance clarity. As with all the circuit diagramspresented herein, values of specific components shown, if any, aremerely exemplary.

[0051] Diversity, as discussed with reference to FIGS. 2 and 3, can beachieved by using two of the LNAs described in FIG. 5 (or another LNAdesign) with a common pair of load inductors (e.g., 622/624—which areused for tuning the frequency to which the device is sensitive) as shownin FIG. 6. The gate voltages of the cascode devices can be controlled bylogic signals control A and control B to turn off the LNA that needs tobe disconnected (e.g., LNA 600 or LNA 602). For example, if LNA 600 wasto be used, then Control B would be grounded, and the four transistorson the right, that constitute LNA 602, would effectively be eliminated.Preferably, LNA 600 is connected to a first antenna, and LNA 602 isconnected to a second antenna. And, with the redundant amplifiers, theantennas are more directly connected to the amplifiers.

[0052] An implementation consistent with diversity as implemented inFIG. 6 has an additional advantage in that much less physical space istaken up than a design that simply made redundant LNAs. In the redundantLNA design of FIG. 5, the inductors (e.g., 522/524) take up morephysical space than other parts of the circuit, therefore the redundantLNA uses more die space and has greater manufacturing cost. Since theinductors take up a large percentage of space even for a single LNA, adesign consistent with FIG. 6 can be implemented on a die space nearlyequivalent to the die space of a single LNA, but it is a dual LNAimplementation.

[0053]FIG. 7 is a circuit diagram of an example implementation of anon-chip amplifier that enables beam-forming. The amplifier may be, forexample, an LNA or a PA pre-driver. As illustrated in FIG. 7, diversityas well as beam forming, as discussed with reference to FIG. 4, can beimplemented by replacing the cascode devices with switching pairs (e.g.switching pairs 710, 720, 730, and 740) which can steer the current tothe one or the other load inductor. By controlling the gates of thetransistors of the switching pairs with logic signals (A1p, A1n, A2n,A2p, B1n, B1p, B1p, B1n) we can obtain the signal from either antenna Aor antenna B alone, the sum of antenna A and antenna B, or thedifference between antenna A and antenna B. By adding additionalcircuits, these properties may be propagated to triple, quad, or moreantenna arrays.

[0054] For example, the current-steering amplifier topology of FIG. 7can be used either as an LNA or as a PA driver, depending on how theinputs 711, 721, 731, and 741 and outputs 750 and 752 are connected.Control Logic signals are attached to gates on switching pairs 710, 720,730 , and 740 (A1p, A1n, A2n, A2p, B1n, B1p, B1p, B1n). For LNA:antennas are attached to gates at inputs 711, 721, 731, and 741; andreceive mixers are connected to outputs 750 and 752. For PA driver:transmit mixers are attached to gates at inputs 711, 721, 731, and 741;and antennas are attached to outputs 750 and 752.

[0055] A notable variation between FIG. 6 and FIG. 7 is that FIG. 6provides two control (logic) signals so that either amplifier A (e.g.,600) is on or amplifier B (e.g., 602) is on. In FIG. 7, the switchingpairs allow a summing operation. By manipulating the logic signals, theamplifiers may be configured only antenna A, only antenna B, A+B, orA−B. Now, since the antennas are to be located in different places,radiation patterns having peaks and valleys are formed (e.g., see FIG.9). Depending on where a signal that a radio is trying to listen to, or,in the case of a transmitter, where a transmitter is trying to transmitto, there will be an optimum combination that provides the bestcommunications link.

[0056] For example, in terms of receiver, depending on where thetransmitting station is, the receiver may get the clearest reception bysubtracting the two signals received from the different antennas, or byadding them. In one embodiment, the present invention includes aprocessing device that tries different combinations of A, B, A+B, A−B,etc., and then determines which combination/single antenna gives thebest reception, and then that combination is used for the remainingtransmission. In one embodiment, the selected antenna combination isperiodically updated.

[0057] The penalty introduced by the implementation of FIG. 7 is thesmall gain reduction of each LNA with respect to the single antennaimplementation, because of the parasitic capacitance introduced by allthe cascode devices and the lower load inductor value required toresonate it. However, the benefits are considerable and, in mostapplications, easily justify this small gain reduction

[0058] In one embodiment, not shown in FIG. 7, to mitigate the gainreduction penalty, the switching pairs of one of the two LNAs arereplaced with single cascode devices, since it suffices to be able tochange the sign of the signal of one of the two LNAs only. Someasymmetry between the two paths may be introduced, but that disadvantagemay be outweighed by the mitigating effects.

[0059] An implementation of a redundant PA to implement switch diversitywould be to duplicate the PA layout, drive the PAs in parallel, andpower down the amplifier driving the unused antenna. Implementing beamsteering requires more complexity compared to the LNA case, as currentsteering devices in the output stage would reduce the amount of voltagethat can be delivered to the antenna which in turn would reduce the PAefficiency. FIG. 8 proposes an alternate transmitter implementationwhere two sets of current steering drivers (similar to FIG. 7) 805 and810 are used to drive two output stages 815 and 820. The control bits(807 and 812) to the drivers direct the TX signal paths to be driven inphase or complementary, or alternatively, the control bits can powerdown one PA or the other.

[0060]FIG. 9 is a graph of example antenna radiation patterns resultingfrom the circuit of FIG. 8. In FIG. 9, the radiation pattern is shownfor a single antenna, pattern 910 (e.g., antenna A or antenna Btransmitting alone). The difference of antenna A and antenna B is shownas patterns 920A and 920B, and the sum of antenna A and antenna B isshown as patterns 930A and 930B.

[0061] The phase shifting techniques presented above in FIG. 6 and FIG.7 is configured to shift the signal 0 or 180 degrees. However, referringback to FIG. 4, an implementation with programmable phase shifters canimplement additional, or programmable phase shifts of the antennaradiation pattern. Other phase shifting techniques may also be utilized.

[0062] For example, the present invention provides a higher degree ofphase shift programmability by replicating a larger part of the receiveand transmit chains instead of the LNAs and/or PAs only. Phase shift by90 degrees can be achieved by shifting a Local Oscillator (LO) signalthat drives a mixer by 90 degrees. The I and Q components of the LOsignal are often available on-chip and are utilized in this manner toimplement a signal phase shift by 90 degrees. FIG. 13 provides anexample implementation of received signal phase shifting by 0°, 90°, and180° according to an embodiment of the present invention. Antenna A andantenna B each feed received signals to corresponding LNAs 1310 and1320. The amplified signals are combined by a first combiner 1330 toproduce combined signals x and y, which are described as:

(x,y)ε{(A,0), (B,0), (A+B,0), (−A+B,0), (A,B), (−A,B)}

[0063] Therefore, x can be either A, −A, B, A+B, or −A+B, and y can be Bor 0. Mixer 1 multiplies x with a signal LO_(I), (I component of a localoscillator), and mixer 2 multiplies y with a signal LO_(Q) (Q componentof the local oscillator). The LO_(I), and LO_(Q) signals are 90° out ofphase. Adder 1350 then combines each of the x and y phase shiftedsignals to a combined phase shifted signal z. The signal z is describedas:

zε{A,B,+/−A+B,+/−A+jB}, where j ²=−1, and

[0064] it is also noted that the signal jB represents the B amplifiedsignal rotated by 90°. Furthermore, in this implementation, it is alsonoted that Mixer M2 only needs to be powered on when it is desired toobtain z =+/−A+jB because all the other combinations are obtainable viacombiner 1330. Although FIG. 13 is directed to receiving signals, thesame basic architecture described in FIG. 13 may be applied to atransmit chain where signals are combined and phase shifted prior tobroadcast on the antennas.

[0065]FIG. 14A is a radiation diagram for a pair of antennas configuredwithout the additional mixers shown in FIG. 13. The radiation diagram isbased on assumptions of antenna omnidirectivity and that a distancebetween antennas A and B is ½ of a wavelength. A pair of lobes 1410 Aand 1410 B illustrate radiation patterns of antennas A and B (and,conversely, reception sensitivity when receiving signals) for the caseof A+B. Lobes 1420 A and 1420 B illustrate radiation patterns ofantennas for the case of A-B. The bold line highlights the outer edgesof each of the lobes. The present invention includes programming orother logic that recognizes directivity needed for a signal to bebroadcast and directivity strength in received signals. The programmingor other logic also selects the most advantageous combination of, +/−A,B, jB, etc., for broadcast or received signals based on thatdirectivity. Therefore, the bold line illustrates the effectiveradiation pattern of the antenna because the programming and logicallows the best characteristics of each radiation pattern to be takenadvantage of.

[0066] By adding more combinations of antenna patterns and includingadditional programming and or logic to select the additional antennapatterns when needed, the effective radiation pattern of the antennas isfurther increased. FIG. 14B is a radiation diagram illustrating the jBcombinations (B rotated 90°) according to the example implementation ofFIG. 13. Lobe 1440 illustrates the A−jB radiation patterns, and lobe1450 illustrates the A+jB radiation pattern. These additional radiationpatterns are added to those illustrated in FIG. 14A, resulting in aneffective radiation pattern as shown by the bold line in FIG. 14C.

[0067]FIG. 15 provides an example circuit implementation of the LNAs and1st combiner from FIG. 13. Differential amplifier LNA A amplifiessignals A(+) and A(−), and LNA B amplifies signals B(+) and B(−). Logicsignals S1, S2, S3, and S4 control whether LNA amplified signals A(+),A(−), B(+), or B(−) are applied individually or in combination todifferential output signals x(+), x(−), and y(+), y(−). For example, toget an (x, y)=((A−B), 0) from the combiner, logic signals are applied sothat S₁=1, S₂=0, S₃=1, and S₄=0, therefore, the x differential outputseach have +/−A and −/+B applied to them, resulting in an A-B signal.Table 1 provides a logic chart identifying control signals and outputsfor FIG. 15: TABLE 1 S₁ S₂ S₃ S₄ x(+) x(−) y(+) y(+) A 0 1 0 1 A(+) A(−)B(+) B(−) A − B 1 0 1 0 A(−) + B(+) A(+) + B(−) 0 0 −A 1 0 0 1 A(−) A(+)B(+) B(−) A + B 0 1 1 0 A(+) + B(+) A(−) + B(−) 0 0 B 0 0 1 0 B(+) B(−)0 0

[0068]FIG. 16 is a circuit diagram of an example implementation of themixer 1, mixer 2, and adder of FIG. 13. The topology follows a GilbertCell topology, but applied for use in the present invention. Switches S₅and S₆ are closed to shut down mixer 2 under the conditions describedabove.

[0069] The present invention also provides an implementation thateliminates off-chip receive/transmit switches. Off-chip diversity andReceive-Transmit switches are usually implemented as series or shuntswitches. Switches are often implemented with diodes or FET transistors.Open series switches and closed shunt switches are ideally losslessterminations and can be used to reflect the signal power and direct itto a desired device. The present invention includes the implementationof on-chip series or shunt switches as a way to eliminate the off-chipdevices. Such an implementation saves the cost of the external devices,and lowers the system power consumption in the case that the on-chipdevices replace external diode switches, since diodes consume DC powerwhen they are on. More significantly, they can potentially reduce thefront-end signal power loss.

[0070] The on-chip switches, implemented with FET transistors are notideal. Their on resistance is finite, while the lossy capacitance of thesource and the drain represent some finite resistance to the substrateat high frequency. Parasitic series resistance of on switches is lessharmful in terms of power loss when the impedance of the block to whichthe switch is connected in series is high. Parasitic shunt resistance isless harmful when the impedance of the block to which the switch isconnected in series or in shunt is low.

[0071] The input of the LNA is usually very sensitive to any lossycomponents connected to the gate of the input device. If a switch isn'tused at the LNA input, when powered down, the LNA possibly representsonly a small load to the PA, relative to the load represented by thelossy drain region of the large PA output transistors. However, a goodon-chip shunt switch at the PA output can be implemented by using the PAoutput devices, without the need for new switch devices, which willintroduce more losses. Therefore, while in concept this invention wouldrequire two on-chip shunt switches, in practice only the PA shunt switchmay be needed. However, an advantage may still exist when including boththe PA and LNA shunt switches in a design. For example, large amounts ofpower transmitted by the PA may have enough power leakage to the LNAthat the LNA may be in danger of being damaged. In this case, the LNAshunt switch would help prevent damage.

[0072]FIG. 10 is a prior art implementation of switchable power combinerusing parallel devices. Each of a dual PA arrangement includes a shuntswitch that grounds the unused PA output. This basic idea can beextended to transmit/receive switches.

[0073] The present invention leverages from the switchable powercombiner in FIG. 10 to provide an improved transmit/receive switcharrangement for associating a PA or a LNA to an antenna. FIG. 11 is ablock diagram of a transmitter PA 1100 and a receiving LNA 1105operating without external switches in conjunction with a single antenna1110. Each of the components are coupled to a ¼ wavelength wires orequivalent networks 1115 and 1120. And, no grounding switch for the LNA1105 is needed.

[0074]FIG. 11 exploits a property of ¼ wavelength wires that a shortcircuit on one end of the wire appears as an open circuit at the otherend. In the circuit shown, during receive, the shunt switch 1102 on thetransmit (PA) side is shorted to ground. This causes the other end ofwire 1120 to appear as an open circuit, and thus the received signal iscoupled from the antenna 1110 to the LNA 1105 with a minimum of lossonto the transmit circuitry. Thus, the shunt switch 1102 is openedduring transmit and closed during receiving. The shunt switch 1102 isoperated via circuitry and/or programming.

[0075] The same principle applies during transmit mode, when signalscoupled from the PA 1100 to the antenna 1110 with a minimum of loss intothe receive circuitry. In concept, this is accomplished by placing ashorted switch 1107 on the LNA side of wire 1115. In practice, thepresent inventors have found that the loss of signal power duringtransmit is minimal, and may not require switch 1107 at the LNA input.This is due to the relatively small input capacitance of the LNA (inthis implementation). Also, since the presence of a switch at the LNAinput would degrade the receiver performance (even when the switch isopen), the preferred implementation of FIG. 11 uses only the singleshunt switch 1102 at the output of the PA 1110.

[0076] Individuals skilled in the art of RF design can replace the ¼wavelength lines with equivalent lump element circuits or matchingnetworks.

[0077]FIG. 12 is an example implementation of a PA with a built-in shuntswitch according to an embodiment of the present invention. Withreference to FIG. 12, the following operations are performed:

[0078] A) During Transmit, the PA output device delivers power to theantenna Rfout 1210. Switch (A) is closed so that the DC current isprovided to the PA output device 1200. Bias is set at a DC voltageappropriate for amplifying the input RF signal.

[0079] B) During Receive, the shunt switch is active, and no DC powershould be consumed. Switch (A) is open to disconnect DC power from thePA output device. Bias is connected to VDD so that the PA output device1200 forms a shunt-switch to ground. Note that switch (A) can either beplaced between the inductor and PA device 1200 as shown in FIG. 12 orbetween the inductor and supply VDD.

[0080] Although the present invention has been described herein withreference to diversity antennas A and B, any number of antennas may beaccommodated by adding additional circuits and/or other hardware asdescribed herein, which will be apparent to the ordinarily skilledartisan based upon review of the present disclosure.

[0081] The present invention is intended to be applicable to any rangeof frequencies and numerous antenna combinations. In one embodiment, anRF front end according to the present invention is configured for IEEE802.11a wireless communications. In another embodiment, the RF front endis configured for 802.11b wireless communications. In yet anotherembodiment, diversity antennas are utilized in an 802.11a and 802.11bcombined radio device. Either the antennas themselves are dual bandantennas, or the one or more of the antennas attached to the RF frontend are specifically for 802.11a communications and one or more other ofthe antennas attached to the RF front end device are specifically for802.11b communications. Again, however, any combination protocols orbroadcast frequencies may be supported by the devices and processeselaborated herein.

[0082] In describing preferred embodiments of the present inventionillustrated in the drawings, specific terminology (e.g., componentvalues, transistor types, differential design, etc.) is employed for thesake of clarity. However, the present invention is not intended to belimited to the specific terminology so selected, and it is to beunderstood that each specific element includes all technical and designequivalents which operate in a similar manner. For example, whendescribing power amplifier and combination of electrical components,including, but not limited to, transistors, resistors, capacitors, etc.may be employed in making that part, and, any other device having anequivalent function or capability, whether or not listed herein, may besubstituted therewith. Furthermore, the inventors recognize that newlydeveloped technologies not now known may also be substituted for thedescribed parts and still not depart from the spirit and scope of thepresent invention. All other described items, including, but not limitedto LNAs, Splitters, combiners, switches, and antennas, etc should alsobe consider in light of any and all available equivalents.

[0083] Portions of the present invention may be conveniently implementedusing a conventional general purpose or a specialized digital computeror microprocessor programmed according to the teachings of the presentdisclosure, as will be apparent to those skilled in the computer art.

[0084] Appropriate software coding can readily be prepared by skilledprogrammers based on the teachings of the present disclosure, as will beapparent to those skilled in the software art. The invention may also beimplemented by the preparation of application specific integratedcircuits or by interconnecting an appropriate network of conventionalcomponent circuits, as will be readily apparent to those skilled in theart based on the present disclosure.

[0085] The present invention includes a computer program product whichis a storage medium (media) having instructions stored thereon/in whichcan be used to control, or cause, a computer to perform any one or moreprocesses of the present invention. The storage medium can include, butis not limited to, any type of disk including floppy disks, mini disks(MD's), optical discs, DVD, CD-ROMS, micro-drive, and magneto-opticaldisks, ROMs, RAMs, EPROMs, EEPROMs, DRAMs, VRAMs, flash memory devices(including flash cards), magnetic or optical cards, nanosystems(including molecular memory ICs), RAID devices, remote datastorage/archive/warehousing, or any type of media or device suitable forstoring instructions and/or data.

[0086] Stored on any one of the computer readable medium (media), thepresent invention includes software for controlling both the hardware ofthe general purpose/specialized computer or microprocessor, and forenabling the computer or microprocessor to interact with a human user orother mechanism utilizing the results of the present invention. Suchsoftware may include, but is not limited to, device drivers, operatingsystems, and user applications. Ultimately, such computer readable mediafurther includes software for performing the present invention, asdescribed above.

[0087] Included in the programming (software) of the general/specializedcomputer or microprocessor are software modules for implementing theteachings of the present invention, including, but not limited to,setting of switches, (e.g., diversity switches, transmit/receiveswitches, etc.), setting PA amplification levels, packet testing, signalstrength evaluation, software mixing, combining, or other functions toimplement any aspect of the present invention.

[0088] Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed and desired to be secured by Letters Patent of theunited states is:
 1. An RF front end architecture, comprising: a set ofmultiple antenna ports; multiple power amplifier PA devices configuredto feed signals to at least one of the antenna ports; multiple low noiseamplifier LNA devices configured to receive signals from at least one ofthe antenna ports; and antenna diversity switches connected to inputs ofthe PA devices and/or outputs of the LNA devices.
 2. The RF front endarchitecture according to claim 1, wherein: each LNA device is pairedwith one of the PAs and configured to receive signals from the antennaport to which its paired PA device is configured to feed signals; the RFfront end architecture further comprising a transmit/receive switchcoupled between each paired PA and LNA and its corresponding antennaport.
 3. The RF front end architecture according to claim 2, whereinsaid transmit/receive switch, for each paired PA and LNA, comprises: ashunt switch that grounds an output of the PA device; a first ¼wavelength wire or equivalent network connected to an output of the PAdevice and the shunt switch at one end and connected to the antenna portat another end; and a second ¼ wavelength wire or equivalent networkconnected to an input of the LNA device at one end and connected to theantenna port at another end.
 4. The RF front end architecture accordingto claim 2, wherein said transmit/receive switch, for each paired PA andLNA, comprises: a shunt switch that grounds an input of the LNA device;a first ¼ wavelength wire or equivalent network connected to an input ofthe LNA device and the shunt switch at one end and connected to theantenna port at another end; and a second ¼ wavelength wire orequivalent network connected to an output of the PA device at one endand connected to the antenna port at another end.
 5. The RF front endarchitecture according to claim 2, wherein said transmit/receive switch,for each paired PA and LNA, comprises: a first shunt switch that groundsan output of the PA device; a second shunt switch that grounds an inputof the LNA device; a first ¼ wavelength wire or equivalent networkconnected to an output of the PA device and the first shunt switch atone end and connected to the antenna port at another end; and a second ¼wavelength wire or equivalent network connected to an input of the LNAdevice and the second shunt switch at one end and connected to theantenna port at another end.
 6. The RF front end architecture accordingto claim 1, further comprising: at least two phase shifters each phaseshifter coupled to an input of one of the power amplifiers; wherein:each power amplifier is coupled to one of the antenna ports; and eachphase shifter is configured to phase shift signals prior toamplification by the power amplifier coupled to the phase shifter. 7.The RF front end architecture according to claim 6, wherein the phaseshifted signals are phase shifted such that when amplified by the poweramplifiers and broadcast from separate antennas each connected to one ofthe antenna ports, a predetermined antenna radiation pattern is formed.8. The RF front end architecture according to claim 7, wherein saidphase shifters are programmable, and said RF device further comprises aprogramming device configured to program an amount of phase shiftperformed by each phase shifter needed to form the predetermined antennaradiation pattern.
 9. The RF front end architecture according to claim1, further comprising: at least two phase shifters, each LNA devicehaving an output coupled to an input of one of the phase shifters; and asignal combiner coupled to an output of each of the phase shifters;wherein: each phase shifter is configured to phase shift signalsreceived by each LNA device so that they can be combined in phase by thesignal combiner.
 10. The RF front end architecture according to claim 9,wherein said phase shifters are programmable.
 11. The RF front endarchitecture according to claim 10, further comprising: a controllerdevice coupled to said phase shifters and configured to adjust a phaseof signals received from the antenna ports and set an amount of phaseshift in each of the phase shifters such that the signals are combinedin optimal phase.
 12. The RF front end architecture according to claim10, further comprising: a controller device; and a set of instructions,when loaded into the controller, cause the controller to perform thestep of adjusting a phase of signals received on each antenna port untila desired gain is achieved by antennas attached to the antenna ports.13. The RF front end architecture according to claim 6, wherein saidphase shifters are programmable.
 14. The RF front end architectureaccording to claim 13, further comprising: a controller device coupledto said phase shifters and configured to adjust a phase of signals to befed to the antenna ports such that a signal broadcast from antennasconnected to the antenna ports provide an optimal antenna radiationpattern.
 15. The RF front end architecture according to claim 13,further comprising: a controller device; and a set of instructions, whenloaded into the controller, cause the controller to perform the step ofadjusting a phase of signals to be broadcast from each antenna portuntil a desired radiation pattern is emitted from antennas attached tothe antenna ports.
 16. The RF front end architecture according to claim1, wherein the PA and LNA devices, and the diversity switches areimplemented on-chip using CMOS technologies.
 17. The RF front endarchitecture according to claim 1, further comprising at least onetransmit/receive switch coupled between the PA and LNA devices and theantenna ports.
 18. The RF front end architecture according to claim 17,wherein each transmit/receive switch, comprises: a shunt switch thatgrounds an output of a PA device; a first ¼ wavelength wire orequivalent network connected to an output of the shunt switch groundedPA device and the shunt switch at one end and connected to an antennaport at another end; and a second ¼ wavelength wire or equivalentnetwork connected to an input of an LNA device at one end and connectedto the switched antenna port at another end.
 19. The RF front endarchitecture according to claim 17, wherein said transmit/receiveswitch, for each paired PA and LNA, comprises: a shunt switch thatgrounds an input of the LNA device; a first ¼ wavelength wire orequivalent network connected to an input of the LNA device and the shuntswitch at one end and connected to the antenna port at another end; anda second ¼ wavelength wire or equivalent network connected to an outputof the PA device at one end and connected to the antenna port at anotherend.
 20. The RF front end architecture according to claim 17, whereinsaid transmit/receive switch, for each paired PA and LNA, comprises: afirst shunt switch that grounds an output of the PA device; a secondshunt switch that grounds an input of the LNA device; a first ¼wavelength wire or equivalent network connected to an output of the PAdevice and the first shunt switch at one end and connected to theantenna port at another end; and a second ¼ wavelength wire orequivalent network connected to an input of the LNA device and thesecond shunt switch at one end and connected to the antenna port atanother end.
 21. An RF front end architecture, comprising: a set ofmultiple antenna ports; at least one power amplifier PA devicesconfigured to feed signals to at least one of the antenna ports; atleast two low noise amplifier LNA devices each configured to receivesignals from one of the antenna ports; and an antenna diversity switchconnected to inputs of the PA devices and outputs of the LNA devices;wherein said at least two LNA devices are part of an IC device and saidPA device is external to the IC device.
 22. An RF front endarchitecture, comprising: a set of multiple antenna ports; at least twopower amplifier PA devices configured to feed signals to at least one ofthe antenna ports; at one low noise amplifier LNA devices eachconfigured to receive signals from one of the antenna ports; and anantenna diversity switch connected to inputs of the PA devices andoutputs of the LNA devices; wherein said at least two PA devices arepart of an IC device and said LNA device is external to the IC device.23. The RF front end architecture according to claim 21, furthercomprising at least two 3-way transmit/receive switches, eachtransmit/receive switch coupled between one of the antenna ports, theexternal PA, and one of the LNA devices.
 24. The RF front endarchitecture according to claim 23, wherein each transmit/receiveswitch, comprises: a shunt switch that grounds an output of the PAdevice; a first ¼ wavelength wire or equivalent network connected to anoutput of the PA device and the shunt switch at one end and connected tothe antenna port at another end; and a second ¼ wavelength wire orequivalent network connected to an input of the LNA device at one endand connected to the antenna port at another end.
 25. The RF front endarchitecture according to claim 23, wherein said transmit/receiveswitch, for each paired PA and LNA, comprises: a shunt switch thatgrounds an input of the LNA device; a first ¼ wavelength wire orequivalent network connected to an input of the LNA device and the shuntswitch at one end and connected to the antenna port at another end; anda second ¼ wavelength wire or equivalent network connected to an outputof the PA device at one end and connected to the antenna port at anotherend.
 26. The RF front end architecture according to claim 23, whereinsaid transmit/receive switch, for each paired PA and LNA, comprises: afirst shunt switch that grounds an output of the PA device; a secondshunt switch that grounds an input of the LNA device; a first ¼wavelength wire or equivalent network connected to an output of the PAdevice and the first shunt switch at one end and connected to theantenna port at another end; and a second ¼ wavelength wire orequivalent network connected to an input of the LNA device and thesecond shunt switch at one end and connected to the antenna port atanother end.
 27. An RF front end, comprising: a set of at least twoantenna ports; at least two power amplifier PA devices each configuredto feed amplified signals to at least one of the antenna ports; and aninput line shared by inputs of each of the at least two poweramplifiers.
 28. The RF front end according to claim 27, furthercomprising at least two phase shifters, wherein each respective phaseshifter has an output coupled to an input of at least one of the PAdevices and configured to phase shift a signal input to the PA devicescoupled to the respective phase shifter.
 29. An RF front end,comprising: a set of at least two antenna ports; at least two low noiseamplifier LNA devices each configured to receive signals from at leastone of the antenna ports; and a signal combiner coupled to each of theLNA devices and configured to combine signals from outputs of each LNAdevice.
 30. The RF front end according to claim 29, further comprisingat least two phase shifters, each respective phase shifter having aninput coupled to at least one output of the at least two low noiseamplifiers and configured to phase shift a signal output from the LNAdevices coupled to the respective phase shifter prior to combination bythe signal combiner.
 31. An RF device, comprising: at least two antennaports; an RF front end having at least two PA amplifiers, each PAamplifier having an output coupled to one of the antenna ports; an RFsignal generating device; and an antenna diversity switch coupled to theRF signal generating device and the RF front end; wherein said antennadiversity switch is configured to direct RF signals generated by the RFsignal generating device to one of the PA amplifiers.
 32. The RF deviceaccording to claim 31, further comprising at least two antennas, eachantenna coupled to one of the antenna ports.
 33. The RF device accordingto claim 32, wherein: at least one of the antennas is a dual bandantenna optimized for use in combined IEEE 802.11a and 802.11b wirelesscommunications.
 34. The RF device according to claim 31, furthercomprising a controller box configured to test reception of signalsreceived on said antenna ports and determine a best receiving antenna,and, based on the tested reception, direct the diversity switch todirect signals generated to the PA coupled to the antenna port havingthe best reception.
 35. The RF device according to claim 31, furthercomprising: at least two transmit/receive switches; and at least two LNAdevices; wherein: each LNA is paired with one of the PA amplifiers andone transmit/receive switch is coupled between each PA/LNA pair and theantenna coupled to the PA amplifier, each transmit/receive switchdirecting signals from the antenna to the LNA, or directing signals fromthe PA to the antenna.
 36. An RF device, comprising: at least twoantenna ports; an RF front end having at least two LNAs, each LNA havingan input coupled to one of the antenna ports; an RF signal receivingdevice; and an antenna diversity switch coupled to the RF signalgenerating device and the RF front end; wherein said antenna diversityswitch is configured to direct RF signals from the one of the LNAs tothe RF signal receiving device.
 37. The RF device according to claim 36,further comprising at least two antennas, each antenna coupled to one ofthe antenna ports; wherein: at least one of the antennas is a dual bandantenna optimized for use in combined IEEE 802.11a and 802.11b wirelesscommunications.
 38. A method of transmitting RF signals, comprising thesteps of: preparing an RF signal for transmission; selecting an antennabest suited for transmitting the prepared RF signals from a set of atleast two antennas; and feeding the prepared RF signals to a poweramplifier coupled to the selected antenna; wherein each power amplifieris coupled to only one of the antennas.
 39. The method according toclaim 38, wherein said step of feeding comprises setting an antennadiversity switch coupled between a device that prepared the RF signaland the power amplifier coupled to the selected antenna.
 40. The methodaccording to claim 38, further comprising the steps of: selecting a setof antennas for transmitting the prepared RF signals on the beam;splitting the prepared RF signals so that one signal has been split foreach selected antenna; phase shifting the split signals as required sothat when transmitted by the antennas, a desired radiation pattern isformed.
 41. The method according to claim 38, wherein: said method isembodied in a set of computer instructions stored on a computer readablemedia; said computer instructions, when loaded into a computer, causethe computer to perform the steps of said method.
 42. The methodaccording to claim 41, wherein said computer instruction are compiledcomputer instructions stored as an executable program on said computerreadable media.
 43. The method according to claim 38, wherein saidmethod is embodied in a set of computer readable instructions stored inan electronic signal.
 44. The method according to claim 38, wherein:said method is implemented in a digital baseband ASIC.
 45. A method ofreceiving RF signals, comprising the steps of: determining at least oneantenna best suited for receiving RF signals; and switching a signalreceiving line to outputs of LNAs each only coupled to one of the bestsuited antennas.
 46. The method according to claim 45, wherein each LNAis coupled to said one of the best suited antennas via atransmit/receive switch.
 47. The method according to claim 45, wherein:said step of determining comprises determining at least two antennasbest suited for receiving RF signals; and the method further comprisesthe steps of, phase shifting each of the RF signals received by each ofthe best suited antennas, and combining the phase shifted RF signals toproduce a single RF signal switched to the signal receiving line. 48.The method according to claim 47, wherein said step of phase shiftingcomprises phase shifting each of the received RF signals so that theyare combined in optimal phase.
 49. The method according to claim 45,wherein: said method is embodied in a set of computer instructionsstored on a computer readable media; said computer instructions, whenloaded into a computer, cause the computer to perform the steps of saidmethod.
 50. The method according to claim 49, wherein said computerinstruction are compiled computer instructions stored as an executableprogram on said computer readable media.
 51. The method according toclaim 45, wherein said method is embodied in a set of computer readableinstructions stored in an electronic signal.
 52. The method according toclaim 45, wherein: said method is implemented in a digital basebandASIC.
 53. An RF device, comprising: means for preparing an RF signal fortransmission; means for selecting an antenna best suited fortransmitting the prepared RF signals from a set of at least twoantennas; means for feeding the prepared RF signals to a power amplifierhaving an output coupled only to the selected antenna.
 54. An RF device,comprising: means for determining at least one antenna best suited forreceiving RF signals; and means for switching a signal receiving line tooutputs of LNAs each only coupled to one of the best suited antennas.55. An RF front-end device, comprising: a diversity switch havingmultiple outputs; multiple antenna ports; and multiple Power Amplifier(PA) devices, each PA having, an input connected to one of theindividual outputs of the diversity switch, and an output exclusivelyconnected to one of the antenna ports.
 56. The RF front-end deviceaccording to claim 55, further comprising at least one LNA device, eachLNA device having, an input connected to one of the antenna ports, andan output connected to one of inputs of the diversity switch.
 57. The RFfront end device according to claim 56, wherein said LNA device isexternal to an IC containing the multiple PA devices.
 58. The RFfront-end device according to claim 55, wherein: said diversity switchincludes multiple inputs; and the RF front-end device further comprisingmultiple Low Noise Amplifiers (LNAS), each LNA having an input connectedto one of the antenna ports and an output connected to one of the inputsof the diversity switch.
 59. The RF device according to claim 55,wherein: each PA input is only connected to one of the outputs of thediversity switch; each LNA output is only connected only to one of theinputs of the diversity switch; and each antenna port is connected toone PA output and one LNA input.
 60. The RF device according to claim59, further comprising at least one transmit/receive switch, eachtransmit receive switch connected to the output of one of the PA devicesand configured to connect/disconnect the PA device from its antennaport.
 61. The RF device according to claim 60, wherein eachtransmit/receive switch comprises: a first set of ¼ wavelength wires orequivalent networks each connected to an output of one of the PAdevices; a second set of ¼ wavelength wires or equivalent networks eachconnected to an output of one of the PA devices; and at least one shuntswitch configured to ground at least one of the PA and LNA devices. 62.The RF device according to claim 59, further comprising at least onetransmit/receive switch, each transmit receive switch connected only tothe input of one of the LNA devices and configured to disconnect/connectthe LNA device from its antenna port.
 63. The RF device according toclaim 62, wherein each transmit/receive switch comprises a set of ¼wavelength wires or equivalent networks and at least one shunt switch.64. The RF front end architecture according to claim 1, wherein: each PAdevice is paired with one of the LNAs and configured to transmit signalsto the antenna port to which its paired LNA device is configured toreceive signals; the RF front end architecture further comprising atransmit/receive switch coupled between each paired PA and LNA and itscorresponding antenna port.